Liquid reaction or treatment chambers find numerous applications for enhancing the treatment of liquids such as a single component liquid, liquid-liquid reaction and/or mixing, liquid-gas reaction and/or mixing and liquid-particulate material reaction and/or mixing. For example, in formulating inks, paints and other viscous materials two or more components (at least one being a liquid) are mixed together in such a treatment chamber to form the applicable solution. Other examples include the simultaneous introduction of various liquids and gases into the chamber to promote certain reactions. This would include the flow of water into the chamber with the introduction of gases such as air and/or oxygen and/or ozone only to mention a few. Also such chambers can be used to induce a variety of chemical reactions such as the decomposition of hydrogen peroxide, emulsion polymerization reactions and the creation of emulsions for emulsion polymerization mechanisms.
In other applications, treatment chambers can be used for the deagglomeration of particles in a liquid stream. This would include the deagglomeration of nano-particles such as pigments used in the formulation of inks. Plus the simultaneous formulation of an ink using these nano-pigment particles. This system can also have the simultaneous exposure to UltraViolet (UV) light to promote certain reactions of fluids or fluid/gas or fluid/gas/solids systems in the ultrasonic chamber. Another application could be in the medical field where a treatment chamber is used in the preparation of pharmaceutical formulations that are composed of powders/liquids and liquids for dispensing for use.
In particular, it is often advantageous to provide the chamber with some agitating mechanism by which liquid is agitated within an elongate column or chamber. By agitating the liquid, a desired reaction (e.g., mixing or other result) may be expedited and thus capable of being achieved in a continuous flow operation. As a result, treatment chambers that facilitate such agitation are particularly useful in continuous flow treatment processes.
Agitation of a liquid may be referred to as static agitation, in which agitation is caused by the particular flow parameters (e.g., flow rate, pressure, etc.) of the one or more liquid components through a column. Static agitation may also occur by directing a flow of liquid past stationary agitating members, such as a helical vane-type construction or other structures disposed in the flow column or chamber that disrupt and thus turbulate the flow of the liquid to be treated. Dynamic agitation is brought about by moving, e.g., rotating, oscillating, vibrating, etc. one or more agitating members (e.g., vanes, fan blades, etc.) within the treatment chamber through which the liquid flows.
One particularly useful type of dynamic agitation of the liquid results from ultrasonic cavitation, a more rigorous agitation, in the liquid. Ultrasonic cavitation refers to the formation, growth and implosive collapse of bubbles in liquid due ultrasonic energization thereof. Such cavitation results from pre-existing weak points in the liquid, such as gas-filled crevices in suspended particulate matter or transient microbubbles from prior cavitation events. As ultrasound passes through a liquid, the expansion cycles exert negative pressure on the liquid, pulling the molecules away from one another. Where the ultrasonic energy is sufficiently intense, the expansion cycle creates cavities in the liquid when the negative pressure exceeds the local tensile strength of the liquid, which varies according to the type and purity of liquid.
Small gas bubbles formed by the initial cavities grow upon further absorption of the ultrasonic energy. Under the proper conditions, these bubbles undergo a violent collapse, generating very high pressures and temperatures. In some fields, such as what is known as sonochemistry, chemical reactions take advantage of these high pressures and temperatures brought on by cavitation. However, the growth and violent collapse of the bubbles themselves provides a desirably rigorous agitation of the liquid. Cavitation that occurs at the interface between the ultrasonically energized liquid and a solid surface is rather asymmetric and generates high speed jets of liquid, further agitating the liquid. This type of cavitation is particularly useful, for example, in facilitating a more complete mixing together of two or more components of a liquid solution.
It is known to pack some treatment chambers with a bed of particles, such as in the manner of a fluidized bed reactor. The particles are thus in the flow path of the liquid within the treatment chamber and further facilitate treatment of the liquid. However, where such particles are present in the chamber, the chamber must be configured to prevent the particles from being carried (or forced) out of the chamber by the liquid flowing therein. For example, a screen element may block the outlet of the chamber to block the particles, but not the liquid, from exiting the chamber. While such a screen element can be effective, there is a risk that the particles will agglomerate or otherwise build up on the screen element and reduce the flow rate of the liquid out of the chamber, thereby increasing the pressure in the chamber.
There is need, therefore, for a continuous flow ultrasonic liquid treatment chamber that takes advantage of the benefits of ultrasonic energy to treat a flowing liquid, particularly where particles are used in such a treatment chamber, while maintaining desired operation conditions of the treatment chamber.